Stroke, Vol 22, 928-932, Copyright © 1991 by American Heart Association
KE Gordon, J Simpson, D Statman and FS Silverstein
We used in vivo microdialysis to determine the impact of a focal
hypoxic-ischemic insult on striatal amino acid efflux in the immature
brain. Microdialysis probes were inserted into the right striatum of
postnatal day 7 rats. To induce hypoxic-ischemic injury, the right carotid
artery was ligated and the animals were exposed to 8% oxygen for 2.5 hours
(n = 22). Rats exposed to ligation alone (n = 10) or hypoxia alone (n = 8)
and untreated controls (n = 17) were also studied. Two hours after probe
insertion, a 30-minute baseline microdialysis sample was obtained. After
arterial ligation, two additional baseline samples were collected. Five
more samples were collected over the next 2.5 hours (in 8% oxygen or room
air). Eight amino acids (glutamate, aspartate, taurine, glutamine, alanine,
serine, glycine, and asparagine) were consistently detected in dialysates
using a high-performance liquid chromatography assay with electrochemical
detection. In untreated controls, amino acid efflux did not change over 4
hours. During hypoxia-ischemia, efflux values fluctuated widely, with
marked intra-animal and interanimal variability. Efflux peaks for each
amino acid were defined as values greater than the highest control mean
value plus two standard deviations. Glutamate efflux peaks (greater than 7
pmol/min compared with 2 pmol/min at baseline) were detected in no controls
and in eight hypoxic-ischemic rats (p = 0.006, Fisher's two- tailed exact
test). Taurine efflux peaks (greater than 75 pmol/min compared with 10
pmol/min for controls at baseline) were detected in 10 hypoxic-ischemic
rats and one control (p = 0.01) and in seven of the eight animals in which
glutamate efflux peaks occurred (p = 0.006).(ABSTRACT TRUNCATED AT 250
WORDS)
ARTICLES
Effects of perinatal stroke on striatal amino acid efflux in rats studied with in vivo microdialysis
Department of Pediatrics, University of Michigan, Ann Arbor 48109-0570.
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